Electrical apparatus



J. WILKINSON.

ELECTRICAL APPARATUS.

APPLICATION FILED omzs. 1915.

1,306,570. I Patented June 10, 1919.

2 SHEETS-SHEET I. 3/

Figl.

Inventor": James Wilkinson, 5 Hisoqttorneg.

I. WILKINSON. ELECTRICAL APPARATUS. APPLICATION FILED DEC-28.1915.

v UNITED STATES PATENT orF oE.

JAMES WILKINSON, 0F PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF YORK.

ELECTRICAL APPARATUS.

Specification of Letters Patent. Patented J une 10, 1919.

Application filed December 28, 1915. Serial No.69,108.

merged, water cooled transformers are ex amples of the sort of apparatus to which my invention in its complete form is especially applicable; oil switches are a type of apparatus in connection with which the principal part-of my invention. is of interest.

My invention is thus of quite general applicatlon, but for the sake of simplicity and clearness of description, and: since it is of v particular interest in transformers, I shall fluid, and the problems which may be solved a mostly describe it as it is related to that type of apparatus; I shall also in many instances, likewise for simplicity and clearness, refer-to the fluid submerging the electrical apparatus as oil and the fluid for artificially cooling the submerging fluid as water, the fluids now in most common use for these purposes. The general application of my invention to all submerged electrical apparatus using oil or some other submerging by my invention though they will vary with the apparatus to which my invention may be applied, will be readily understood from the description of its application to transformers. I

According to the most' common practice prior to my invention, transformer tanks;

and likewise oil switch tanks, are provided with covers carried by the tank walls, and

the fluids submerging the electrical appara;

tus only partially fill the tanks; gas filled spaces, more or less open to the atmosphere, are left between the surfaces of the submerging fluids and the covers to allow for the exgases as may be generated in the :submergpensions and contractions of the submerging fllllds as thelr temperatures rise and fall during the operation of the apparatus.

Such gas chambers possess various undesirable features. For QXQTIPlG HOb only does each chamber contain air but t receives such qualities.

ing oil, some of which may form explosive mixtures with the gastherein, which, should they become ignited may result in destructive explosions; further, in receiving air from the surrounding atmosphere as the transformer ,and submerging oil cools and contracts, the chamber receives such moisture and other foreign matter as may at the time be in suspension in the atmosphere, and passes them on to the submerging fluid to the detriment of ts insulating and cooling suggested for. overcoming certain of such undesirable features, such as filters for the air passing between the atmosphere and the gas chamber, and such as the elimination of the gas chamber by completely filling the tank with the submerging oil, taking care of the expansion of the oil by means of tanks external to the transformer tanks proper. All such expedients, however,

themselves possess more or less undesirable features such as requlrlng constant attention, or devices external to the tanks, or lack simplicity or suflicient ruggedness, or some olther features desirable in apparatus of this c ass.

The principal object of my invention is to provide tanks or devices for submerged electrical apparatus unaccompanied by such undesirable features, which take care within themselves of the expansion and contraction of the submerging oil and in' which the gas chamber is substantially eliminated.

I accomplish this object by providing a tank which is substantially completely filled with the submerging oil and which freely changes in capacity as the oil expands and contracts. More particularly, I prefer to carry the cover of the tank up and down substantially in contact with substantially the entire surface of the oil as the oil expands and contracts. as by carrying or floating the cover on the contained fluid. In addition. I preferably provide means for suitably guiding the cover with respect to the tank and for suitably sealing all openings through or about the cover to exclude all contact between the atmosphere and the fluid within the tank as the cover rises and falls;the seal about theedges of the cover may be suitable to pass to [the atmosphere any excess gases within the tank, such for Various expedients have been example as those generated therein, or a separate'passage to the atmosphere may be provided for such excess gascs,or the separate passage may be arranged to pass gases at a lower pressure and in smaller volumes than the seal, taking care of normal conditions, but being supplemented by the seal to pass such larger volumes as may be generated under abnormal conditions. features of suitable seals and separate passages to pass excess gases to the atmosphere may be of interest in connection with other types of tanks. The leads may, or may not, pass through the movable cover; such bushings as may be necessary may be carried by the cover as heretofore even though the latter float on the submergingfluid. If desirable a connection may be made between the tank and the floating cover for grounding the cover to the tank.

My invention as thus outlined may be applied to substantially all types of tanks in which electrical apparatus is submerged in insulating or cooling fluids. Another object of my invention, applicable when such fluids are artificially cooled as by water cooling coils submerged in the fluid within the tank, is to control the operation of such cooling. means so as to equalize the operating temperatures of the submerging fluid and the electrical apparatus therein. I do this by using the expansion and contraction of the tank to control a valve or other device governing the flow of water (or other coolingfluid) through the cooling coils or, cooling chamber. If the cover is adapted to rise and fall as before indicated, a connection between the cover and watergoverning device may start the operation of the cooling device when the submerging fluid reached a predetermined temperature, and hence, expanded to apredetermined degree and raised the cover to a predetermined point, and stop the flow of water at another position of the cover. This temperature may be something like that which it is desired the submerging fluid shall assume when the apparatus is operating continuously at about full load. The transformer is therefore at no time cooled much more than is necesary. N o cooling water is wasted by unnecessary cooling and the insulating materials of the transformers are not subjected to unnecesary expansions and contractions tending to break them down. 7

In the ;aecompanying drawings I have illustrated certain embodiments of my in-- vention. Figure 1 is .an elevation, partly in section, of a portion of an oil submerged, water-cooled transformelgtthe cover of the tank floating on the submerging oil. Fig. 2 is a sectional'view on a larger scale, of the fluid seal between the cover and the tank, and one of the guides for the cover. Fig. 3

isi'ja sectional ,view through the primary These a part of another tank illustrating particularly another manner of carrying a lead through a floating cover.

Referring to Fig. 1: The upwardly opening tank 6, the Water-cooling coils 7, and the transformer 8 are substantially like those heretofore common. In accordance with my invention however, the tank 6 is provided adjacent its top, with an upwardly opening annular well which is formed by the lip 9 and the annular bottom 10 which are attached to and concentric with, and within the walls of the tank 6. The cover ,of the tank comprises a substantially flat base portion 11 and upwardly extending edges 12, forming what is in efl'ect a boat. The diameter of this cover is somewhat shorter than the internal diameter of the annular lip 9, as shown in Figs. 1, 2, and 4; this difference in diameter is sufficient to allow the cover to readily move vertically and to allow the escapeof any gas that may be generated within the tank. The edges 12 of the cover extend upward, primarily in order that the cover together with the bushings and such other devices as it may carry, may float on the oil 17 submerging the transformer 8. As the load on the transformer 8 changes therefore, and the oil 17 submerging it expands and contracts, the cover will rise and fall, but will always maintain engagement with substantially the entire surface of the submerging oil. In the construction now being described these edges extend above the top of the tank when the cover is in its lowermost position, that is, when the oil of the tank is contracted to substantially the smallest volume contemplated, and carry two downwardly extending concentric'lips 18 and 19. The lip 18 extends into the an nular-well of the tank and is disposed somewh. t closer to the internal lip or wall 9 than to the external wall of the tank 6; the lip 19 is external to the tank and completes a cover 18'and above thesurfacesof the liquid 17 and 20; as indicated above, this may be made of very small-volume. It will be apparent that any gaseous pressure within the tank will tend to lower the level of the oil 20 between the lips 9 and 1 8, and ultimately escape below the lip 18 to the atmosphere. Since the lip 18 is located nearer the lip 9 than to the wall ofthe tank, gases within the tank may escape to the atmosphere at a. pressure (per square inch) lower than the pressure at which the atmosphere may enter the tank. A ga e 35, indicates the position of the surface of The only gas chamber within the oil 20 within the annu Ill lar well and hence the gaseous pressure within the tank. The connections of this gage are particularly illustrated in Fig. 4. The liquid seal completed by the'oil is particularly well adapted for releasing lar e volumes of gas to the atmosphere, but since in many cases this seal must be of considerable depth, on account of the range of movement of the tank cover, it may be possible for the gaseous pressure within the tank to reach undesirably high values. To relieve this pressure and maintain it at low values, I provide a primary valve 40 which, while genetrflly not able to pass such large volumes of gas s as the seal of the liquid 20, may pass to t e atmosphere at lower pressures than the seal, such small volumes of gas as are to be anticipated in the normal operation of the device. Thisprimary valve 40 is, in effect,

a second liquid seal but of considerably lower head than the oil 20 of theannular well. This valve 40 comprises a hollow cylinder containing oil '42 into which a pipe 43 extends. The pipe 43 opens into the annular space within the tank between the edges 12 and lip 18 of the cover. At the lower end of the pipe 43 is an upwardly opening. elbow 44 carrying a cage 45 for positioning a-ball 46 adapted to. float on the oil '42. This cage gas'within the tank. In order that such ob- 1 is so disposed that if, by any reason, the level of the oil 42 falls below the open end of the ,elbow 44, the ball seats in this opening and excludes contact between the atmos here and the interior of the tank through t is valve. A connection 55 is provided between the atmosphere and the interior of the valve 40 above the surface of the oil 42. As before pointed out, the head of the primary valve 40 is lower than the head within the annular well at the top of the tank, that is, the distance between the top of the elbow 44 and the surface of the liquid 42 is less than the distance between the surface of the liquid 20 and the lower edge of the lip .18; thus gas be tween the'edges 12 and the lip 18 may force an exit to the atmosphere'through the priobserved; hence the valve .40 serves the double purpose of passing gas to the atmosphere and an indicator of the generation of servations may be readily made; the valve 40 is preferably located on the walls of the z tank6 andso far below the top as maybe tened to the cover in any desired way,

necessary to bereadily inspected; to allow the cover to rise and fall the pipe 43 is flexible. The flexible cable 50 connected between the cover and the tank 6 firmly grounds the cover to the tank.

As the cover rises and falls it may be guided and held in position with respect to the tank by the external lip 19 alone or, if desired, other guiding means as the arms 22 carrying rollers 23 engaging-with runways 24 on the walls of the tank may be provided. The number of such guiding arms will, of course, depend to a considerable extent on the size of the tank. A

In the constructions illustrated the high voltage leads pass through the cover. In the construction illustrated in Fig. 1, each lead is provided with a bushing 29 which is carried by the cover and which may be fasthough preferably the joint is air tight. Each lead 30 is substantially a rigid rod which is firmly fixed to the transformer at its lower end and to some stationary device 31 at its upper end. Firmly attached to the upper end of each rod is a cylinder 32. Operating within this cylinder is a hollow piston 33 carried by the bushing 29. Each rod 30 passes freely through its bushing and the corresponding piston. As the cover rises and falls, the piston 33 likewise rises and falls in the cylinder 32, but the two always form an air-tight joint between the atmosphere and the'interior of the bushing 29, and hence exclude contact between the atmosphere and the submerging oil 17 through the body of the bushing. i

The flow of water through the cooling coil 7 is controlled by the valve 54. This valve is opened .and closed by the rod 65 which carries near its top two heads or pins 56 and 57. An arm 58 attached to the outer lip 19 of the cover surrounds the rod between the two heads 56 and 57. These heads and the arm are so positioned that When the oil submerging the transformer has reached the temperature which it is desired it should assume when the'transformer is something like fully loaded, and the oil has correspondingly expanded, the arm 58, raised by 11 the cover and engaging the head 57 of the valve, holds this valve so far open that sufficient water flows through the coils 7 to maintain the oil at this temperature- On the other hand, when the load on the transformerhas fallensubstantially below such predetermined value, and the submerging oil has correspondingly contracted and-the cover fallen, the arm 58 leaves the head 57 allowing the valve 54 to close, or, if necessary, engages with the head 56 and moves the valve toward this closed position. The heads 56 and 57 are separated such a distance that the cover may rise with the ex ansion of the submerging oil without openmg the valve until the desired predetermined temperature of the oil has been reached. It will be seen that this connection between the I 7 floating cover and the valve tends to equalize The insulating qualities of the oil are, therefore, maintained and the maximum expansion and contraction of the materials of the transformer and the rate of such expansion and contraction are materially reduced, both of which are conducive to long life for the apparatus. The transformer tank of Fig. l is particularly adapted for outdoor service, the cover being provided with atop, or roof, 60, for preventing the accumulation of rain or snow. Where the transformer is to be used for indoor service this top or roof may be omitted and the lead bushings carried on the base 11 of the cover as illustrated in Fig. 4.

In Fig. 4. a type of bushing and lead is illustrated which may be usedwhenever the lead is not too heavy to flex readily. In this case the lead 61 is firmly fastened within the bushing. 62 and does not slide therein as in the construction of Fig. 1. This lead '6l-is flexible between the lower end of the bushing and the transformer, and between the upper end of the bushing and the stationary member 63. These flexible portions of the lead allow the cover to rise and fall without disturbing the connections.

While I have described the principle of my invention and the best mode I have contemplated-for applying this principle, other modifications will occur to those skilled in I this art and I aim in the appended claims to cover all modifications which do not involve a departure from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. The combination with a tank, a liquid therein and electrical apparatus submerged in said liquid, of a single protecting cover for said tank arranged to float on the surfaceof said liquid, and a fluid seal between the edges of the cover and the tank excluding contact between said submerging liquid and the atmosphere.

2. The combination .with a tank, a liquid therein and electrical apparatus submerged in said liquid, of a single protectin cover for said tank'arranged to float on' t e surface of said liquid, and a fiuid seal between the edges of the cover and the tank excluding contact between said submerging liquid and the atmosphere and a gage connected to said seal for indicating the position of the sealing fluid therein.

3. The combination with a tank, a liquid therein and electrical apparatus submerged in said liquid, of a single protecting cover for said tank floating on said submerging liquid, a liquid seal between the edges of said cover and tank and an insulating bushing for a lead from said apparatus carried by saidcover.

4. The combination with a tank, a fluid therein and electrical apparatus submerged in said fluid, of a single protecting cover for said tank carried by said fluid near the surface thereof, a fluid seal between the edges of said cover and said tank, and means electrically connecting said cover and tank.

5. The combination with a tank, a liquid therein and electrical apparatus submerged in said liquid, of a single protecting cover for said tank floating on said liquid, a fluid seal excluding contact between said liquid and the atmosphere and a valve mounted on said cover connected with the interior of said tank above the surface of said submerging liquid allowing the escape of gas formed in said tank.

6. The combination with a tank, a fluid therein and electrical apparatus submerged in said fluid, of a single protecting cover the escape of gas generated in said tank. 7

and provided with means for preventing the entrance of the atmosphere into said tank therethrough. 1

8. The combination with a tank, a fluid therein and electrical apparatus submerged in said fluid, of a single protecting cover for said tankfloating on said fluid, a fluid seal excluding contact between the atmosphere and said submerging fluid and a fluid valve fastened to the exterior of the tank below the top thereof and of lower head than said fluid seal allowing the escape of gas gener ated in said tank. v

9. The combination. with an upwardly opening tank provided. with an upwardly opening annular well adjacent the top thereof, a liquid in said tank and electrical appa- ,sai

ratus submerged in said liquid, of a single protecting cover for said tank floating on said submerging liquid and provided with a downwardly extending annular lip within said well, and a second liquid within said well completing a liquid seal for said tank as the cover rises and falls with the expansiqln and contraction of the submerging liqu1 e 10. The combination with an upwardly opening tank provided with an upwardly opening annularwell adjacent the top there of, a liquid in said tank and electrical apparatus submerged'in said liquid, of a single protecting cover for said tank floating on said submerging liquid and provided with a downwardly extending annular lip within well, said lip being located nearer to c the inner than to the outer wallof said well,

and a second liquid in said well completing a liquid seal for said tank.

' 11, The combination with an upwardly opening tank provided with an upwardly opening annular well adjacent the top thereof, a liquid in said tank and electrical apparatus submerged in said liquid, of a single on said submerging liquid and provided with two downwardly extending concentric annular lips, one within and the other external to said annular well, the latter completing a cover for said annular well, and a second liquid within said well completing-a liquid seal for said tank as the cover rises and falls with the expansion and contraction of the submerging liquid.

12. The combination with an upwardly opening tank provided with an upwardly opening annular well adjacent the top thereof, a liquid in said tank and electrical apparatus submerged in said liquid, of a single'protecting cover for said tank float- 7 mg on said submerging liquid and provided with a.downwardly extending annular lip within said well, a second liquid within said well completing a liquid seal for said tank as the cover rises and falls with the expansion and contraction of the submerging liquid, and means between the tank and cover positioning the cover with respect to the tan 13. The combination with an upwardly open ng tank provided with an upwardly opening annular well adjacent the top there of, a liquid in said tank and electrical ap- Jparatus submerged in said liquid, of a single" protecting cover for said tank floating on said submerglng liquid and provided with two downwardly extending concentric annular lips, onewithin and the other external to said annular well, the latter completing a i cover for said annular well, aseconddiquid' within said well completing a liquid seal for said tank as the cover risesand falls with I the expansion and contraction of the submerging liquid, and downwardly extending guides carried by the cover engaging the tank walls positioning the cover with respect to the tank.

14. The combination with an upwardly opening tank provided with an upwardly opening annular well adjacent the top thereof, aliquid in said tank and electrical appa-. ratus submerged in said liquid, of a cover for said tank floating on said submerging liquid and provided with a downwardly extending annularlip within said well, a second liquid within said well completing a liquid seal for said tank as the cover rises and falls with the expansion and contraction of the submerging liquid, a liquid valve of lower head than the liquid in said seal fastened to the exterior of said surface of the submerging liquid.

15. The combination with an upwardly opening tank provided with an upwardly opening annular well adjacent the top thereof, a liquid in said tank and-electrical apparatus submerged in said liquid, of a cover for said tank floating on said submerging liquid and provided with-a'downwardly extending annular lip within said well, a second liquid within said well completing a liquid seal for said tank as the cover rises and falls with the expansion and contraction of the submerging liquid, a liquid valve of lower head than the liquid in said seal fastened to the exterior of said tank below the top thereof, a flexible pipe connecting said valve with the interior of said tank through said cover above the surface of the submerging liquid and means for-preventing the entrance of the atmosphere into said tank through said liquid valve.

16. The combination with a tank, a liquid therein, electrical a paratus submerged in said liquid and a coo ing coil for said liquid, of a cover for said tank floating on said liquid, a valve for controlling the flow of a cooling fluid through said cooling coils and a connection between said cover and valve for opening and closin said valve as the cover rises and falls wit the expansion and contraction of the liquid and allowing a limited movement of the cover without a movement of the valve.

17. The combination with a liquid, electrical apparatus submerged in said liquid trical apparatus and expanding and con- Ill) trac'ting as the liquid therein expands and v contracts, of a cooling device for said liquid, a cooling liquid adapted to circulate throu h said cooling device, means controlling t e flow of said cooling liquid through said 0001- ing device and a connection between said tank and controlling means increasing the cooling device for said liquid submerged therein having a cooling fluid flowing therethrough, a regulating means for controlling the flow of cooling fluid through said device 15 and an operative connection between said cover and said'means whereby the flow of said cooling fluid is regulated in response to the movement of said cover.

In witness whereof, I have hereunto set 20 my hand this 22nd day of December, 1915.

JAMES WILKINSON. 

